Water Efficiency Calculations

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Water Efficiency Calculations

Water Efficiency Calculations involve assessing and implementing measures to promote responsible water usage in compliance with Building Regulations. As per the April 2010 update, Requirement G2 mandates that all newly constructed or converted dwellings undergo water efficiency calculations. This requirement emphasizes the installation of fittings and fixed appliances that promote efficient water usage to mitigate excessive water consumption.

The regulations stipulate a maximum allowance of 125 litres of potable water per person per day. This allocation comprises 120 litres for internal water use per person per day, with an additional 5 litres per person per day reserved for outdoor water usage. Notably, certain local authorities, particularly in areas such as London and the South, may impose even stricter targets.

Failure to adhere to these regulations can have repercussions on the Standard Assessment Procedure (SAP) calculation, potentially resulting in a lower Energy Performance Certificate (EPC) rating. Thus, compliance with water efficiency standards is essential for ensuring environmental sustainability and optimizing energy performance in buildings.

When Should You Get Water Calculations Done?

We have learnt the importance of getting your Part G calculations completed at the design stage. It is far easier to change the bath you are planning on buying than it is to change the bath you have already bought and installed.

We’ve also found that the easiest ways to ensure a pass on your water efficiency calculations are to concentrate on the products with the highest use factor. A use factor is the multiplication applied to the capacity/flow rate of your fittings, based on how often they are likely to be used. Therefore, it’s good to be aware of the items that have a high use factor, and make those ones as energy efficient as possible.

For example, in a property with both a shower and a bath, the shower has a use factor (multiplication) of 4.37, compared to the bath’s use factor of 0.11. This is based on the assumption that showers get used an awful lot more than baths in most households. In this instance, it’s worth putting a lot of emphasis on purchasing a shower with a low flow rate.

We encourage you to have a chat with us for further information on water efficiency calculations.

Why Should You Get Water Calculations Done?

In addition to adhering to regulatory requirements, it is paramount for all of us to acknowledge and mitigate our environmental impact.

Aligning your development with the maximum limit of 125 litres of potable water per person per day not only promotes environmental responsibility but also helps curtail excessive water consumption.

Beyond ethical considerations, opting for fittings with low flow rates and capacities can yield substantial cost savings on your water bill. Embracing water-efficient practices not only benefits the environment but also contributes to economic sustainability.

Which Appliances And Products Are Affected?

To accurately assess water efficiency, various fixtures and appliances within a property require specific measurements:

Toilets
The capacity of the toilet flush, distinguishing between single flush and dual flush options, is crucial. This capacity is typically measured in litres.

Taps
The flow rate of both kitchen and bathroom taps is essential information, typically quantified in litres per minute.

Baths
The total capacity of the bath up to the overflow point is measured in litres.

Showers
The flow rate of each shower, expressed in litres per minute, is a critical factor in water efficiency calculations.

Dishwashers
Water usage for dishwashers is determined by the amount of water consumed per place setting. This metric reflects the volume of water used in a standard cycle, divided by the number of place settings accommodated by the dishwasher.

Washing Machines
Efficiency in washing machines is gauged by the amount of water utilized per kilogram of dry load. This measurement is derived from the volume of water consumed in a standard cycle, divided by the washing machine’s capacity in kilograms for dry clothes.

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